Knitting a sweater pattern - cast on sleeves

I am knitting a sweater pattern. The first step is to knit the back part of the sweater. I am almost done with this step and the next step is calling for cast on sleeves. It starts by saying to cast on x number of stitches. My question is the knitting needle I am using is a US 9 and it is about 10" long. I am not sure if I am supposed to move to another longer needle or how am I suppose to cast on the sleeves. In the materials section, it doesn’t say anything about another set of needles or what other tools to use. It does say that after casting on the sleeves I will have a lot more stitches then when I first started the back part of the sweater. I need help understanding how to do this.

How many stitches are on the needles now, just for the back?

How many stitches do you add for the sleeves? and I imagine the same number of stitches on each side, right?

It likely will be easier if you’re using a circular needle. You can knit flat (back and forth) on them, you don’t have to join in a circle. They hold a lot more stitches then straights.

Do you have a link to the pattern or information about where to find the pattern? That might help.

Did your pattern tell you to use 10" needles? If so and there is nothing about a longer needle maybe it is constructed differently that you think. You usually don’t make a whole back piece and then add on sleeves.

Maybe you knit the sleeves totally separate and sew them on.? But that doesn’t explain what you said here:

It does say that after casting on the sleeves I will have a lot more stitches then when I first started the back part of the sweater.

Maybe you don’t have the whole back done but only up to the armholes. Some sweaters are made that way, make the back to the armholes and then cast on stitches on each side for the sleeves. But then you would probably need a longer needle. Circular like Marilyn said.

Unless the sleeves are added to the back, you drop the yarn when you’re done with the back, and either bind off the sts or place them on a holder. Then taking a new end of yarn, cast on the sts separately. But that’s just a guess - a link to the pattern itself would be helpful. You can also look ahead to the finishing instructions and see if it says to sew the pieces together, or if there’s a drawing see if it shows the back and sleeves all in one piece or fi they’re separate pieces.

I am two rows from finishing a sweater knit in the same way. I used 14 inch needles and am making the smallest size sweater using ww yarn. After I cast on the second sleeve there is absolutely no room left on the 14 inch needles - the stitches are as squished as anything I’ve ever seen. I’d recommend moving up to at least a 14 inch needle or a circluar if possible. Just FYI, my pattern didn’t give any advice as to needle length either.

I plan to do more of these sweaters and am going to get a circlular just for them. You’ll find that as you get farther along into the sleeves, the working needle is going to get really heavy. I think that being able to rest a circlular on a table or in my lap will alleviate that.

Best of luck in finishing your sweater.